The problem, I think, is repetition.
Any adventure through the wilderness is "exciting" because it's constantly fraught with peril, the body is pushed to extremes and must be cared for, the scenery changes constantly but gradually, and lots of little choices need to constantly be made between the big choices. Gamifying this experience for a roleplay setting in an interesting way is tricky/impossible, because you're basically making the same skill checks over and over again. Think "Oregon Trail." That's a cool game, but it doesn't translate to dynamic roleplay.
One way to do it is making the journey a series of "dungeon crawls," just in the outdoors. Get from here to there, and in between is basically a maze of obstacles (you can't just go straight through in the wilderness), and different choices (in direction or whatever) result in different encounters or challenges (just like a dungeon).
You can add the darkness of night and weather (and relevant time constraints -- get around the cliff and find shelter before the storm/nightfall -- to such dungeony problems as monsters/plants/people/monster-plant-people (hunted by a lanotaur manhunter? sat next to a carnivorous tree? attracted a t-rex to the brontosaurus you killed for food?), natural traps (quicksand, rapids, etc.), cool/horrifying ruins of the past, etc.
Another aspect of wilderness travel and survival, that becomes significant in short time in the real world, is the relationship between the adventurers. This is a bit hard to mimic among the players, because they don't actually feel the stress of travel, and they usually want to get along as a heroic team (or something like that). In a related example, if you play a squad of soldiers, you're usually not playing a bunch of stressed out rooks getting spooked by everything and struggling to keep discipline when the crap hits the fan. You're usually playing a relatively thoughtful squad of steel eyed soldiers. Sometimes the players may want to be the fool who gets too curious and hilariously causes a mountain full of orcs to attack (maybe the roll a hatchling dragon is supposed to play, in Rifts), but basically everyone gets along and the drama is limited to words.
I can see two options here: 1, make sure every spat, either in game or real, has dire consequences. That argument they had costs them needed time (maybe the manhunter on their trail catches up, or a pack of dinosaurs stalked them while they were yelling at each other and they're surrounded, etc.); 2, introduce problematic NPCs (save a bunch of folks from a splugorth slaver, follow a guide or guides -- any sort of companion(s) will do).
In any case, I'm a big fan of making the wilderness of Rifts, especially outside the Domain of Man (therefore the wilderness includes the entire Northeast, from Cape Cod to through the Appalachians) incredibly dangerous (and the Magic Zone, because it's constantly coughing up all sorts of bad, should be even worse in terms of encounters). The books give you things like Splugorth, Shemmarians, Archie, Mechanoids, mutant barbarians, prospectors, dinosaurs, and Native Americans in that region. But I truly think the constant imminent danger needs to be made clear.
For example, see this story (among many) in Outside Magazine:
https://www.outsideonline.com/1825851/consumedThe tagline basically spoils it anyway, so I'll go ahead and summarize the salient points.
First, an amazing adventure kayaker breaks all sorts of records Kayaking dangerous rivers in Africa. His process is informative. No river, even the largest, is completely navigable. Many rivers we think of as navigable today are only that way because of man-made locks and dams (most of which are long gone in Rifts). To break a kayaking record, he has to navigate more of the water than was done before. Where another man may have portaged a certain stretch of river, he attempted via kayak. (see also the history of portaging [https://en.wikipedia.org/wiki/Portage --but please find more significant sources, and I'm sure your imagination will be sparked], just to get an idea of how fur trappers, and what have you, had to navigate the Northeast, and other places, before it was the "Northeast").
He would meet up with a companion at predesignated points along the long rivers he navigated. Sometimes, between meetings, he'd have to camp by himself on the banks of the rivers, fearing the crocodiles, the hippos, the lions, the warring peoples, with no possible protection from the dangers. Every night's sleep was a gamble.
But he lived, and became famous. Eventually he wanted to retire, but a couple other adventurous soles wanted his help navigating the Congo. He was the only person on earth who could help them, as he had done parts of it himself. The most fascinating and tragic part of the story follows. There was a war in the Congo. All the dead people caused the crocodile population to explode. The three had become quite good at spotting hippos and crocs. They could splash the water with their paddles to make the hippos show their heads (imagine how often they had to do this -- I backpacked the Talkeetnas in Alaska, which are mostly rolling tundra with long sightlines, but every crest of every hill, and every bunch of bushy willows, and we shouted "Hey Bear," just in case, so we wouldn't spook the monsters). They'd spot crocs slink into the water as they passed, and they increased their speed, hoping to outpace the reptiles.
They passed a village, a river village, that could no longer use the river, because so many of their people had been taken by the madly reproducing crocs. They saw three small crocs enter the water and increased their speed as normal. Tense, but they'd lived this long. Then, unseen until the last second, an 18 foot crocodile raised itself from the bottom of the river, pulled the fearless guide off his kayak, and dragged him down to death.
The croc knew how to eat a man off a boat.
Translate this to Rifts. Much of our wilderness fears the sound of a gun, and dislikes the presence of people. Most wild animal attacks happen because of an animal's fear. Sometimes, like the croc in a war zone, they learn to like the taste of human. But mostly, the shark is "tasting" you, or the bear is flipping out because you spooked it while it was digging for ground squirrels, or the hippo just doesn't want you near its mud.
In Rifts, the sound of gunfire, or a car engine, or talking, means food for anything that eats meat, just as surely as a kayak means a nice squishy morsel sits on top for a sneaky 18 ft croc. And that's just the animals. Warring factions in the jungle have nothing on demons, necromancer cabals, dragons, Splugorth, and territorial/paranoid people with magic and MD weapons. That 18 foot croc is everywhere, always, except you need the equivalent of a tank to kill it. And you're also being stalked by someone intelligent for some reason.
The players' smallest choices should have large consequences. Even if they choose to go the "correct" way, and avoid a trap you set for them the other way, show them that they barely escaped with their lives ("as you crest the hill, you see a large pack of horrible stuff in the valley where you almost chose to go"). They need to get water and food. Make them think for it, make them walk to the water carefully, and hunt quietly. They should know they only get moments to carve up a kill before the monster comes smelling blood.
If they don't have the requisite skills to deal with the wild, give them a guide who can teach them (and then betray them?). I never try to kill players. I will save them with reinforcements before it comes to that (unless they really walked into the problem stupidly). I want the story to play itself out. A story of survival is all about thoughtfulness, fear, perseverance, and small choices becoming big choices (an RL example: cross some slippery wet rocks with a pack on your back and twist your ankle in the middle of nowhere and you're a dead person--so you better make a big deal out of some little wet rocks and the way you step on them).
The trick is to keep this engaging and exciting. I think they can and should see new things each session. The old lessons should be repeated quickly ("we remember to approach the water super carefully this time") without fuss, and new lessons should appear. A new monster can be fantastic in and of itself (think of Jurassic Park, and seeing the herds, and then the sick triceratops, and then the goat disappears because the T-rex is there, and then the velociraptors get out). People on the way with different motivations (homesteaders, refugees, slavers, robots on patrol, natives defending their land) provide just as much stimulation. Beg the aggressive Iroquois for safety from the monsters hot on their trail. Save the slaves from the slavers, and get directions to something useful -- and that useful thing should feel like an award worth millions to the struggling adventurers, as the choice to put themselves in harm's way to save the slaves while the characters were on the edge of starvation themselves was almost too much to bear.
I love this kind of story. Rifts is a pure post-apocalypse, but instead of desolation and nuclear winter, the apocalypse was caused by both an explosion of "life energy," and an explosion of life. All kinds of it, all over the place. And it's all struggling to balance itself out, while being constantly inundated with new invasive species. Exhausting and thrilling. I hope you can turn it into a great story.